Ca isotope, oceanic anoxic events and the calcareous nannoplankton
(2023) In Dissertations in Geology at Lund University GEOL02 20231Department of Geology
- Abstract
- Research of past calcareous nannoplankton abundances is essential for understanding their role in climate change of today, as well as being able to constrain the timing of their emergence. This research is however limited by preservation issues of nannofossils. A proxy for the abundance of calcareous nannoplankton would thus be useful. As calcareous nannoplankton are the largest producer of calcium carbonates today, and as the production of calcium carbonate affects the isotopic composition of seawater, the isotopic fractionation trend of calcium is proposed to be such a proxy. To control this proposition, Ca isotopic data and nannofossil accumulation rates were collected, both covering specifically oceanic anoxic events - OAEs. These are... (More)
- Research of past calcareous nannoplankton abundances is essential for understanding their role in climate change of today, as well as being able to constrain the timing of their emergence. This research is however limited by preservation issues of nannofossils. A proxy for the abundance of calcareous nannoplankton would thus be useful. As calcareous nannoplankton are the largest producer of calcium carbonates today, and as the production of calcium carbonate affects the isotopic composition of seawater, the isotopic fractionation trend of calcium is proposed to be such a proxy. To control this proposition, Ca isotopic data and nannofossil accumulation rates were collected, both covering specifically oceanic anoxic events - OAEs. These are periods with distinct increases and decreases in nannofossil abundance, facilitating subsequent assessment of correlation between the two trends. There was indication of a positive correlation in the two Cretaceous OAEs but a negative correlation in the lower Toarcian, implying a positive correlation since the Cretaceous. Further testing with more precise methods is warrented to determine whether calcium isotopic fractionation could be a proxy for calcareous nannoplankton abundance and assist research that could be of critical value today. (Less)
- Abstract (Swedish)
- Forskning om tidigare förekomster av kalkbildande nannoplankton är avgörande för att förstå deras roll i dagens klimatförändringar, samt för att kunna fastställa tidpunkten för deras uppkomst. Denna forskning begränsas dock av begränsat bevarande av nannofossil. En proxy för abundans av kalkbildande nannoplankton skulle därför vara användbar. Eftersom kalkbildande nannoplankton är idag de största producenterna av kalciumkarbonat, och eftersom produktionen av kalciumkarbonat påverkar den isotopiska sammansättningen av havsvatten, föreslås den isotopiska fraktioneringstrenden för kalcium vara en sådan proxy. För att testa denna hypotes samlades data om kalciumisotoper och nannofossilens ackumuleringshastigheter, båda specifikt relaterade... (More)
- Forskning om tidigare förekomster av kalkbildande nannoplankton är avgörande för att förstå deras roll i dagens klimatförändringar, samt för att kunna fastställa tidpunkten för deras uppkomst. Denna forskning begränsas dock av begränsat bevarande av nannofossil. En proxy för abundans av kalkbildande nannoplankton skulle därför vara användbar. Eftersom kalkbildande nannoplankton är idag de största producenterna av kalciumkarbonat, och eftersom produktionen av kalciumkarbonat påverkar den isotopiska sammansättningen av havsvatten, föreslås den isotopiska fraktioneringstrenden för kalcium vara en sådan proxy. För att testa denna hypotes samlades data om kalciumisotoper och nannofossilens ackumuleringshastigheter, båda specifikt relaterade till oceaniska anoxiska händelser (OAE). Dessa är perioder med tydlig ökning och minskning i abundans av nannofossil, vilket underlättar en bedömning av korrelationen mellan de två trenderna. Det fanns indikationer på en positiv korrelation i de två OAE under Krita, men en negativ korrelation i den under lägre Toarcian, vilket antyder en positiv korrelation sedan Krita. Ytterligare tester med mer precisa metoder behövs för att kunna avgöra om isotopisk fraktionering av calcium kan vara en proxy för abundans av kalkhaltiga nannoplankton, vilket kan bidra till forskning som kan vara av kritiskt värde idag. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9216126
- author
- Bollmark, Viveka LU
- supervisor
- organization
- course
- GEOL02 20231
- year
- 2023
- type
- M2 - Bachelor Degree
- subject
- keywords
- calcareous nannoplankton, nannofossil, Ca isotope, oceanic anoxic events
- publication/series
- Dissertations in Geology at Lund University
- report number
- 657
- language
- English
- id
- 9216126
- date added to LUP
- 2026-01-07 10:42:42
- date last changed
- 2026-01-07 10:42:42
@misc{9216126,
abstract = {{Research of past calcareous nannoplankton abundances is essential for understanding their role in climate change of today, as well as being able to constrain the timing of their emergence. This research is however limited by preservation issues of nannofossils. A proxy for the abundance of calcareous nannoplankton would thus be useful. As calcareous nannoplankton are the largest producer of calcium carbonates today, and as the production of calcium carbonate affects the isotopic composition of seawater, the isotopic fractionation trend of calcium is proposed to be such a proxy. To control this proposition, Ca isotopic data and nannofossil accumulation rates were collected, both covering specifically oceanic anoxic events - OAEs. These are periods with distinct increases and decreases in nannofossil abundance, facilitating subsequent assessment of correlation between the two trends. There was indication of a positive correlation in the two Cretaceous OAEs but a negative correlation in the lower Toarcian, implying a positive correlation since the Cretaceous. Further testing with more precise methods is warrented to determine whether calcium isotopic fractionation could be a proxy for calcareous nannoplankton abundance and assist research that could be of critical value today.}},
author = {{Bollmark, Viveka}},
language = {{eng}},
note = {{Student Paper}},
series = {{Dissertations in Geology at Lund University}},
title = {{Ca isotope, oceanic anoxic events and the calcareous nannoplankton}},
year = {{2023}},
}